There are a variety of hinge structures with different configurations in the prior technologies. For example, two connecting boards are usually rotatably connected via a hinge structure. Such a prior hinge structure usually includes an upper blade and a lower blade symmetrically arranged, wherein the upper blade is fastened onto the first connecting board with screws, the lower blade is fastened onto the second connecting board with screws, and a rotating shaft is provided in the rotating shaft holes of the upper and lower blades and held in place, thus connecting together the upper and lower blades. This type of hinge structure, though simple, requires the blades to be fixed on the corresponding connecting boards in advance during assembly. The blade installation is time-consuming. And, when not installed in the proper alignment position, the two connecting boards may encounter difficulty in opening and closing due to friction. Then, one must adjust the clearance between the two connecting boards by disassembling and retightening the positions of the upper and lower blades, which is both time and labor consuming. Overall, improvements are needed for the prior hinge structure.